Steam-boiler furnace



Apri 10, 1928. 1,665,923

w. A. GILCHRIST STEAM BOILER FURNACE original Filed Feb. e. 1919 2 sheets-snee: 1

W mi f 4x: f 967, I

i WM 9 w. A. GlLcHRlsT STEAM BOILER FURNACE April 1o, 192s.

original Filed Feb. 8. 1919 2 Smets-sluwe*b 2 Patented Apr. 10, 1928.

UNITED STATES WILLIAIVI A. GILCHRIST, OF NEW YORK, N. Y.

STEAM-BUTLER FURNACE.

Application filed February 8, 1919, Serial No. 275,837.

The invention relates to steam boiler fur naces and has for its object an improved construction for securing greater economy in the use of fuel. Inasmuch as the surfaces of steam boilers are at all times much cooler than the ignition temperature of combustible gases, it has been found that the economical u. i of any fuel requires that provision be made for securing; complete combustion of the burning` gases before they have access to the relatively cool surface of the boiler. lfhile this is noticeably important in the use of fuels from vvhich large amounts of hydrocarbon gases are envolved because of the separation of carbon in the forni of smoke Ywhen some of the highly heated hydrocarbon rases are suddenly cooled by contacty with the boiler shell. it is scarcely less important in the use of solid fuel containing only a small proportion of volatile constituents. In the latter case the flamesy may principally comprise burning carbon monoxide and .vhile a sudden chilling; ol this gras does not result in the production of smoke. there is nevertheless a loss of economy if combustion of the gas is not complete. rllhe invention accordingly contemplates an arrangement wherein the path of travel of the gases from the fuel bed to the boiler is of such length that there ample time for combustion to be completed before the boiler is reached.

The invention further contemplates that in the use of solid fuels, the heat resultingfrom combustion of the gases evolved from the fuel shall be effective in stimulating re action in the fuel bed. .lo Patent No. 1.166.870, issued to me January l, 19115, it was shovvn that when large amounts of moisture are present in the fuel. as in the ea::e of Wet saw-dust7 bagasse and the like, the heat generated by the combustion of the volatile constituents could advantagreously be made to assist in the dryino of the fuel bed. On the other hand. the d' iructive distillation of dry volatile fuels such as coal containing' a large proportion of volatile constituents, and the drying and destructive dif'- tillaton of fuels such as lignite which contain both moisture and a high percentage of volatile combustible matter. also require heat and this suggests the desirability of employino` an arranggementy similar to that employed for the Wet fuels first mentioned. Furthermore. the maintenance of a high temperature in the fuel bed tends to a more rapid Renewed .Tuly 4, 1924.

burning of the fuel whereby increased capacity will be obtained from reaction upon the fuel bed of the heat generated by the combustion of the gases, even though the character of the fuel is such that neither drying' no1' destructive distillation are involved in the process of combustion to any extent. In any case. the heaty available for reaction upon the l'ucl bed, Whether for promotingl destructive distillation alone, as in the case of bituminom coal, for both drying and destructive distillation as in the case of lignite, Wet saw-dust and the like, or merely for stimulating ignition, as in the case of anthracite coal, Will be greater and a greater economy in the use of the fuel will result if provision is also made for avoiding` any contact of the generated gases with the relatively'cool surfaces of the boiler until atte 1 heir combustion has been completed.

In the accompanying drawings Fig. l is a central longitiulinal` sectional view illustrating, the improved furnace applied to a return tubular boiler.

Figs 2 and 3 are each similar to Fig. 1, but show the furnace applied to Water tube boilers of two different types.

In carrying out t-he invention the tire box 10 preferably takes the form usually provided in so-called Dutch oven or extended front furnaces. The fuel bed, as 11. is carried upon grates 12 through which air yfor combustion .is admitted and it is sm'mounted by a masonry arch 13 which becomes incandescent and thus assists in maintaining` a high temperature Within the tire box. ln ca.-;e saiv-dust or the like is to be used as fuel. the arch 13 is preferably formed with a feed opening 111 through which the fuel is delivered for maintaining the fuel bed 11 in the form of a cone, but Whether or not the fuel is normally to be supplied through the arch 13, the front 1.5 of the furnace is desir-ably equipped with the usual fuel feeding and clean out doors 16. 1T.

As in my said former patent, the fire box 1() is preferably wide open at its rear end and is in direct comnumicat-ion with a combustion chamber 18 of substantial size. At. its rear end the combustion chamber 18 1s bounded by an upright masonry Wall 19 which faces direct-ly into the chamber of the lire box 10. The Wall 19 also becomes incandescent and by radiation and reflection of heat also assists in maintainingr a high temperature Within the fire box. The upright form of the wall 19 is important both in providing that its inner surface shall face directly into the fire box chamber and in avoidinr any accumulation thereon of ashes or the like which may be carried over with the flames. It is also desirable that this Wall should extend to or above the level of the under surface of the arch 13.

In the present construction, the combustion chamber 18 is also surmounted by a masonry arch7 as 20. To insure sufficient capacity in the combustion chamber 18 and to provide space for an outlet flue 21 extending rearwardly over the wall 19, the level of the arch 20 is preferably substantially above that of the arch 13. This relative arrangement of the two arches 13 and 2O has the further advantage of providing room for a masonry front wall Q2 for the upper portion of the combustion chamber. As all of the masonry walls surrounding the chamber of the tire box 10 and the combustion chamber 18 will become highly heated, combustion of these gases is stimulated rather than checked by contact with these walls and ample opportunity is afforded for combustion of the gases to be completed before they come in contact with any relatively cool surface.

Vhether the boiler is of the return tubular type illustrated at 23 in F i0'. 1, or of one of the water tube types conventionally represented at Q4, 2, and 35, Fig. 3, little opportunity is afforded for direct radiation of heat from the fuel bed, as 11, onto the boiler. It follows that substantially all of the heat is to be transmitted to theboiler by convection. Provision is accordingly made for insuringr a complete. and long continued contact of the products of combustion with the boiler surfaces.

When the furnace is to be used 'n' 1h a return tubular boiler7 as 23. (Fig. l) the outlet flue Q1 preferably leads upwardly, as at 25, to the underside of the boiler where it communicates with a passage 26 extendingl to the rear end of the boiler. Under these circumstances, the iioor 27 of the passage. is desirably quite close to the boiler shell and an intin'iate Contact of the tlue gases with thel boiler surface during their travel to the rear end of the boiler is insured.

Then the furnace is to be used with a water tube boiler, as 2li (Fig. 2) an etlicient transmission of heat from the products of combustion to the boiler will be obtained if the outlet liuc 9.1 communicates with the first pass, as 28, of the boiler and a floor 29 is extended inm'iediatcly under the lower row Il() of boiler tubes in line with the second and third passes 3 32. In each case the arrangement of fine passages is such that in their travel from the outlet flue 21 of the furnace to the stack 38 or 341, the products of combustion are so confined as to be at all times in close proximity to the boiler surfaces.

The improved furnace may also be advantageously used with an upright water tube boiler, as 35, (Fig. Then so used the outlet fine 21 of the furnace preferably communicates with the first pass, as 3G, of the boiler immediately over the lower drum 37.

Owing to the fact that the chamber 18 is of large volume the travel of the gases through it is relatively slow and the interposition of this chamber between the l'ire box and the boiler insures that ample time is alforded for the combustion of the burning' eases to be completed before they come in contact with the boiler surfaces.

Vhile the walls 19, 22, and arches 13, 20, will usually be composed of refractory clay products. employed in the form of brickv` tile or the like, the term masonry7 appearing' in the accompanying claims is not intended to impose any limitation with re spect to the particular composition of the refractory material employed, or the form in which it is used.

Vertical enlargement of the combustion chamber 18 by the elevation of the arch 2() above the level of the arch 13 permits of a. relatively closer location of the heat refleeting wall 19 with respect to the fuel bed without corresponding reduction in the volume of the said combustion chamber.

Likewise the provision for preventing loss of heat from the fire box chamber to the relatively cool surfaces of the boiler shell is of especial importance in the use of low grade fuel since it is otherwise ditcult to maintain suiiiciently high furnace temperatures for rapid drying and destructive distillation of these fuels.

I claim my invention:

1. ln a. furnace, in combination` a grate for supporting` the fuel bed, a masonry arch extending` over the fuel bed and constitutingr the roof of a fire box chamber which is open at its rear end fromsubstantially the level of the rear end of the grate to the said arch, a forwardly facing uninterrupted upright masonry wall located beyond the rear end of the grate and extending` from substantially the level of the rear end of the 2Q'ratc to the level of the said arch for directing' heat back upon the fuel bed through the said open rear end of the fire box chamber.` a. second masonry arch located above the level of the first mentioned arch and extendingV rear fardly from the plane of the rear end of the first mentioned arch to the plane of the said forwardly facing upright wall, an upwardly facing masonry 'floor located substantially at the level of the rear cud of the grate and extending from the rear end of Iii) the grate to the said forwardly facing upright wall, the second mentioned masonry arch, the said forwardly facing upright wall and the said masonry floor constituting respectively the roof, rear wall and floor of a combustion chamber adjoining the said fire box chamber and communicating therewith through the open rear end of the same, and a heating Hue leading out of the said combustion chamber.

2. In a furnace, in combination, a grate for supporting the fuel bed, a masonry arch extending over the fuel bed and constituting the roof of a fire box chamber which is open at its rear end from substantially the level of the rear end of the grate to the said arch, av forwardly facing' uninterrupted upright masonry wall located beyond the rear end of the grate and extending from substantially the level of the rear end of the grate to the level of the said arch for directing heat back upon the fuel bed through the said open rear end of the fire box chamber, a second masonry arch located above the level of the first mentioned arch and the top of the said upright wall and extending rearwardly from the plane of the rear end of the first mentioned arch to and beyond the plane of the said wall, an upwardly facing masonry floor located substantially at the level of the r ar end of vthe grate and extending from the rear end of the grate to the said forwardly facing uprightwall, a rearwardly facing uprightmasonry wall springing from the rear end of the first mentioned arch and extending to the forward end of the second mentioned arch, the second nientioned arch, the said forwardly facing upright wall, the saidA masonry floor and the said rearwardly facing upright wall constituting respectively the roof, rear wall, iioor and partial front wall of a combustion chamber adjoining` the fire box chamber and communicating Vtherewith through the open rear end of the same, and a heating flue leading rearwardly out of the said combustion chamber from the opening between the top of the said forwardly facingl upright wall and the second mentioned arch.

3. In a furnace, in combination, a grate for supporting the fuel bed, a flat masonry arch extending horizontally over the fuel bed and constituting the roof of a lire box chamber which is open at its rear end from substantially the level of the rear end of the grate to the said arch, a forwardly facing uninterrupted upright masonry wall located beyond ihe rear ends of the grate and arch and extending from substantially the level of the rear end of the grate to the level of the said arch for directing heat back upon the fuel bed through the said open rear end of the fire box chamber, a second flat horizontal masonry arch located above the level of the first mentioned arch and extending rearwardly from the plane of the rear end of the first mentioned arch to and beyond the plane of the front face of the said upright wall but spaced apart from the top of the said wall to provide a rearwardly direct-ed iue passage over the wall, anv upwardly facing masonry floor located substantially at the level of the rear end of the grate and extending from the rear end of the grate to the said forwardly facing upright wall and a rearwardly facing upright masonry wall springing from the rear end of the first mentioned arch and extending to the forward end of the second mentioned arch, the second mentioned arch, the said forwardly facing upright wall, the said masonry fioor and the said rearwardly facing upright wall constituting respectively the roof, rear wall, floor, and partial front- L wall of a combustion chamber communicating with the said flue passage and adjoining the fire box chamber through the yopen rear end of the same.

d. In a furnace, in combination, a grate for supportingl the fuel bed, a flat masonry arch extending horizontally over the fuel bed and constituting the roof of a firerbox chamber which is open at its rear end from substantially the level of the rear end of the grate to the said arch, a forwardly facing` uninterrupted upright masonry wall located beyond the rear ends of the grate and arch and extending from substantially the level of the rear end of the grate to and above the level of the said arch for directing heat back upon the fuel bed through the said open rear end of the fire box chamber, a second flat horizontal masonry arch located above the level of the first mentioned arch and extending rearwardly from the plane of the rear end of the first mentioned arch but spaced apart at its rear end from the said forwardly facing upright wall to provide a flue passage between the arch and wall,y an upwardly facing masonry {ioor located at substai'itially the level of the rear end of the grate and extending from the rear end of the grate to the said forwardly facing upright wall and a rearwardly facing upright wall springing from the rear end of the first mentioned arch and extending to the forward end of the second mentioned arch, the second mentioned arch, the said forwardly facing upright wall, the said masonry floor and the said rearwardly facing upright vall constituting respectively the roof, rear wall, floor, and partial front wall of a combustion chamber communicating with the said flue passage and adjoining the fire box chamber through the open rear end of the same.

5. In a furnace, the combination of means for supporting a fuel bed, a masonry arch extending over the fuel bed and constituting the roof of a fire box chamber, a combustion chamber unobstructedly communicating with 'tio l l l) one side of the lire box chamber' from the roof thereof to said supporting nieans and comprising a masonry top Wall located above the level of said arch and'extending rearwardly beyond the rear end of said arch, and rear and side Walls extending upwardly from the level of said supporting Vmeans to a point above the level of said arch, said rear Wall facing said fuel bed and constructed to reflect and radiate heat through said coinbustion chamber against said fuel bed, and a flue extending frein said combustion chainber through Which'the products of combustion are delivered.

6. The inethod of burning solid fuel containing volatile constitutents, which consists in delivering the solid fuel. to be burned into a chamber, admitting air to the chamber' into which said fuel is delivered, radiating and reflecting heat downwardly against said fuel in said chamber to drive ofl.' volatile portions thereof, retarding the flow of said driven off volatile portions in aV space directly rearwardly of and unobstructedly communicating with and in proximity to said solid fuel, radiating and reflecting heat downwardly into and also laterally into and through said retarded portions against said solid fuel, the radiated and reflected heat directed against the solid fuel serving to assist in driving ofl the volatile portions thereof, and the radiated and reflected heat directed into said volatile portions serving to 4ell'ect the completion of the combustion thereof, and delivering the final products of combustion derived freni the solid and volatile portions of said fuel to the point of utilization of the heat so produced. i

7. rlhe niethod of burning solid fuel containing volatile constituents, vvhiel'i consists in delivering the fuel to be burned into a chamber, admitting air tol said delivered fuel, driving ofi the volatile portions of said fuel by radiating and reflecting heat both downwardly and laterally against said fuel, retarding the lioiv of said driven olf volatile portions in a space directly rearwardly of and in unobstructed connnunication With the whole height of said chamber, radiatingand reflecting heat both vertically and laterally into said retarded volatile portions to effect the complete 'combustion thereof, and delivering the resultant products of combustion against 'the surface to be heated.

WiLLrAr/i a. Gunnersr. 

